No wonder people think of the secret services as farce or fiction. What is one to make of an organisation whose leaders have names like Dummy Oliver, Blinker Hall, Biffy Dunderdale, Lousy Payne, Buster Milmo, Pay Sykes, Tar Robertson, Barmy Russel and Quex Sinclair (not to be confused with his successor but one, Sinbad Sinclair)? It’s no good reassuring the reader that in the transition from Victorian days, when men called even their closest friends by their surnames, to the present time, when not to know the first name of a casual acquaintance makes it almost impossible to address him without appearing pompous or supercilious, nicknames like Stubby, Toby or Tubby came to be used as a gesture to informality, particularly in the Army and Navy. The reader is likely to think that such men are preposterous and what they do ludicrous. Even in fiction, the secret services are no longer heroic. Gone are the days when Sapper’s Jim Maitland would sun-bathe himself to a frazzle in order to pass in a burnous as an Arab in Tripoli or thwart the machinations of Baron Stockmar in the Sudan (‘It’s the game, Dick: The Great Game. The only game in the world worth playing’).

The rot set in with that lacklustre fellow Ashenden. His adventures, while accurate in detail, reflected Somerset Maugham’s own failure in organising a network. The spy-master has been degraded by Graham Greene into a shabby down-at-heel anonymous creature who will identify an innocent colleague with the mole he is hunting and kill the wrong man. For him Philby and Co are the modern equivalents of heroic Jesuit priests plotting against Elizabeth. In Le Carré’s world the dingy agents of the KGB and MI6 are interchangeable. Who can forget A.J.P. Taylor’s jibe that no spy ever told his masters anything of value they could not have gleaned from the press? Or Malcolm Muggeridge’s chronicles of his wasted time in the farce of paying agents in Lorenço Marques during the war? Perhaps Cyril Connolly said the last word on the spy story when in ‘Bond strikes camp’ he pictured 007 being nearly seduced by a C monstrously attired in drag.

The spy story continues to flourish, but no longer do upper-class heroes outwit von Stumm and Hilda von Einem as they did in Greenmantle. Giles Railton, the hero of John Gardner’s novel, is a scion of the landed gentry and works in the mysterious upper reaches of the Foreign Office. There he recruits his offspring and nephews and nieces into the ranks of the secret service, just in time for the First World War. But all unknown to Cumming (the original C) and Kell, the first head of what became MI5, or to Dummy Oliver, the Director of Naval Intelligence, and Blinker Hall, head of Room 40 in the Admiralty, who appear as characters in the interests of verisimilitude, Giles Railton is a mole. His kinsmen are playthings in his hand: the devoted and stupid are exposed as German agents, the young and gallant are betrayed and imprisoned in Germany or face a firing-squad. He works towards a German victory but for a higher end – to bring about revolution. At some time this paragon of the Establishment suffered a sudden conversion to Bolshevism. It sounds improbable but, after all, sudden conversions occur. ‘Personally, I would have had the watchers out on St Paul for a long time if I had been in charge of the Christian secret service when he came blundering into Damascus yelling that he’d gone blind, and Christ was the Messiah.’ Railton does his work only too well and on the last page we see one of his younger kinsmen, who disappeared in 1917 in Soviet Russia with other British agents, back in England in the Thirties, at Cambridge, briefing the undergraduate Donald Railton who has already been recruited as a mole.

This is stirring stuff. But verisimilitude in thrillers is not achieved by introducing Cumming and Kell from real life. It is achieved by the authenticity of the jargon (Le Carré) and of the conversation. Kell would never have asked if he could call a man by his first name five minutes after meeting him. Nor is it credible to listen to the Kaiser briefing his spies. The authentic upper-class milieu is better conveyed in Bertie Denham’s Two Thyrds. This book again involves a traitor and spans two generations from the Second World War to the present day. The author, who is the Conservative chief whip in the House of Lords, really knows how the upper classes talk and, as a master of deals behind the scenes, has written a story of singular ingenuity and suspense. Probably in revenge for years of listening to speeches from the benches opposite, he makes his villain a Labour intellectual who becomes a life peer and bears the transparent soubriquet of Lord Frost.

And yet the modern intelligence services owed at one time a considerable debt to the writers of spy stories – in particular to William Le Queux and Phillips Oppenheim. Le Queux’s hero, Duckworth Drew, whose name rhymed with his own and whose appearance matched his own self-image – ‘unobtrusive, of perfect manner, and a born gentleman’ – is first found outwitting the French Foreign Minister by offering him a cigar ‘drugged with a solution of cocculus indicus’. But after the entente, Le Queux was quick to switch villains and, following Erskine Childers’s Riddle of the Sands, unravelled German plans for the invasion of England. Within a few months, Le Queux had got Field-Marshal Lord Roberts and Harmsworth to believe there were 50,000 German waiters spying in London. No, 80,000 German soldiers, said Roberts, employed mostly on the railways. No, 350,000 German soldiers, said Colonel Driscoll DSO, working as moles. The King spoke of his nephew the Kaiser planning to land an army corps and proclaim that, as a grandson of Queen Victoria, he was ready to free the King from ‘the Socialistic gang which is ruining the country’; Parliament voted funds to build eight Dreadnoughts when the Admiralty had asked for only six; and the Committee of Imperial Defence set up in 1909 created what was later to become MI5 under Vernon Kell with a staff of one clerk. Le Queux was an absurd figure, and the Liberal ministers Esher and Haldane kept their heads and refused to countenance the evidence of deranged informers or the forgeries which it had by then become financially worthwhile to manufacture. In fact, the Geman network consisted of a few penniless part-time agents whom Kell put in the bag directly war started. But Le Queux continued to believe his own yarns and did much to fan the spy mania in the First World War.